Rotary drilling bit



Nov. 25, 1958 T. A. WHITE 2,861,779

ROTARY DRILLING BIT Filed July 12, 1956 THOMAS A. WHITE INVENTOR.

ATTORNEY sub 12, as shown in Figure 1.

United States Patent ROTARY DRILLING BIT Thomas A. White, Quanah, Tex.

Application July 12, 1956, Serial No. 597,426

Claims. (Cl. 255-61) This invention relates to rotary drilling bits for drilling oil and water wells, and it has particular reference to the type of bit having multiple blades capable of being detached from the body for replacement or reconditioning, such as described in Letters Patent No. 2,656,153, dated October 20, 1953, and issued to Thomas A. White, and

the principal object of the invention resides in the novel' construction of both body and blades whereby the blades are securely connected to the body.

An object of theinvention is that of providing a drilling bit capable of fast and economical cutting operations in both exploration and production drilling, and providing means whereby the cutter blades can be changed from time to time without undue shut-down delays, and thus insure more rapid and economical completion of the well than can be accomplished by conventional one-piece bits whose blades are integral with the bit body and shank.

It is a further object of the invention to provide a body element formed with-suitable grooves and recesses by which the cutter blades can be readily attached thereto through interlocking lugs and projections engaging the grooves and recesses in the body,- and affording an arrangement by which the blades are secured against displacement by the end of the drill stem or sub to which the bit is attached in drilling operations.

Broadly, the invention contemplates the provision of a drilling bit having detachable blades or cutting elements but providing for securement of the blades only by the device by which it is detachably secured to the drill stem, and in such manner as to resist loosening or displacement of the blades or cutter elements under the rotary and axial forces of the drilling operations imposed thereon.

While the foregoing objects are paramount, other and lesser objects will become manifest as the description proceeds, taken in connection with the appended drawings in which:

Figure 1 is an elevational view of the invention showing the cutter blades detachably supported on the body, and showing the internally bevelled lower end of a drilling sub, partially cut away, for retaining the blades.

Figure 2 is a perspective illustration of one of the cutter blades.

Figure 3 is an elevational view of one of the cutter blades showing a locking web and an opposing dowel formed on its head.

Figure 4 illustrates, in elevation, a modified blade showing opposing locking webs on its head.

Figure 5 is a plan view of one form of bit body, showing the arrangement of longitudinal slots and locking recesses for the webs, and

Figure 6 illustrates, in plan, another formof body having both recesses for the Web and the'dowel to accommodate the blade shown in Figure 3.

Accordingly, the invention comprises a body 10 formed with a threaded pin 11 for attachment to the internally "Ice annular shoulder 13 formed about .the base of the pin a 11, as shown particularly in Figures 5 and 6, and has a plurality of circumferentially spaced longitudinal slots 14 formed therein.

Each of the slots 14, in the form of the'invention shown in Figure 5, has an inclined recess 15 on each side extending into the shoulder 13, and these recesses are wedgeshaped and have their wider sides opening into the side walls of the slots 14 to receive the wedge-shaped and triangular webs 16 formed beneath the head 17 of the blade member 18 shown in Figure 4 by which this element can be securely attached in each of the slots 14 in threaded box of the lower end of a drill stem or drilling The body 10 has a flat the manner shown in Figures 1 and 5. In Figure 6 is shown a modification of the interlocking device for the modified blade 18 illustrated in Figure 3 which has a web 16 formed on one side thereof and.

a dowel 19 depending from its opposite side beneath its head 17. The web 16 engages the recess 15 adjacent the slot 14 of the body 10 and the dowel 19 enters the bore I 20 on the opposite side of the slot 14. It is apparent that in either arrangement shown in Figures 5 and 6,,

against the bevelled heads 17 thereof and against the shoulder 21 formed about the base of the bevelled surfaces 22 of the heads 17, as illustrated in Figure l.

When the blade members 18 are assembled-about the body 10 each forms a segment of a cylinder so that the bevelled surfaces 22 of each is continuous and annular, likewise the shoulders 21 which provide an annular seat for the lower rim 23 of the drilling stem or sub 12 and the internally bevelled surface 23' of the member 12 seats about the surface 22 of the members 17. Each blade 18 extends radially from the body 10 and its front or cutting face is substantially aligned with the longitudinal axis of the body 10, as illustrated in Figures 5 and 6. A hardened cutting edge 24 is applied by any suitable process to the outer vertical and bottom edges of the blades 18. The body 10 has a passage 25 formed longitudinally therethrough for drilling fluids.

The invention is designed to enable the tool operator on the rig to remove and install the blades 18 with a minimum of effort and time by either removing the body 10 from the drill stem or sub 12 or unthreading the same from the latter sufliciently to uncover the bevelled surfaces 22 of the heads 17 of the blades 18, as in the manner shown in Figure 1, so that the blades can be lifted out of the body 10 and replaced, whereupon the drill stem or sub '12 can be rethreaded to seat upon the heads 17. Obviously such an arrangement will securely lock the blades 18 againstdisplacement while drilling.

Manifestly the structure herein shown and described is capable of certain changes and modifications from time to time, by persons skilled in the art, and such changes and modifications as may be considered as falling within the spirit of the invention may also be considered as falling within the scope of the appended claims.

What is claimed is:

1. In a rotary drilling bit for oil and water wells having a body member formed'with a threaded pin for connection to a drill stern, a shoulder formed on said body member about said pin, the said body member having a plurality of circumferentially spaced longitudinal grooves therein opening at their upper ends in said shoulder, a recess formed on at least one side of each of said grooves in said shoulder, a cutting blade, having a head member thereon, seated in each of said grooves and a web on said head member engaging said recess, each of said heads having a curvature about said pin segmentally conforming thereto and having a bevelled upper surface engageable by a drill stem threaded on said pin.

2: In: rotary-drilling bit having a body'member'and a threaded pin portion on said body member, an annular shoulder on said body member about said. pin, the said body member'having a plurality of' circumferentially spaced grooves formed 'longitudinally'thereof and open to said shoulder, a' recess formed in the upper endof one side of each of said grooves, a cutter blade seated' in each of said'grooves-and having a curvedheadportion' engaging said shoulder and segmentally' embracing said" pin portion,- means on said head portion of each of said blades seated'in said'recesses; a bevelled surface formed on each of said head portions inclined downwardly from said pin portion and engageableby the tapered inner surface of a drill stem threaded on-said pin" portion.

3; In a-rotarytype drillingbit' having a body and detachable blades on said" body, a threaded pin on said body and an annular shoulder'formed about said-pin, a,

plurality of grooves formed longitudinally of said body and-opening into'said shoulder; at leastone recess formed insaid shoulderandextending into saidgroove, a cutter blade seatedineach of said grooves and having a curved head portion" segmentally embracing said pin portion and'the-said shoulder, a web formed on said head portion seated in saidrecess-in each groove, a bevelled sur-' face on each of said head portions of said blades, and a drill stem having an internally bevelled surface engageable with said head portionswhen threaded on'said pin portion.

4. Ina rotary drilling bit having detachable cutter blades, incombination with a 'drill'stem and sub, a body member having'a'threaded'pin connected to said drill stem, a shoulder formed about said pin, a plurality of grooves formed longitudinally of said body and spaced circumferentially thereof, a recess formed on at least one side of each of said grooves in said shoulder, a cutter blade in each of said grooves having a curved head seated on said shoulder and segmentally embracing said pin, a web member formed on at least one: side of said blade engageable with said recess, and a bevelled surface on each of said heads engageable-by the internal bevelled surface of a drill stem threaded onsaid pin 5. In a rotary drilling bit having a body portion and a threaded pin for threaded-connection to a bit sub on a drill stem, an annular shoulder on said body about said pin, the said body having a plurality of grooves formed longitudinally and spaced circumferentially thereof and open to said shoulder, a recess formed in at least one side of each of said grooves in said shoulder, a cutter element seated in each of said grooves'and having a curved head member resting on said shoulder and segmentallyengaging said pin, a web formed on each of said. head members seated in each of said recesses, and a bevelledsurfaceon each of said head members engageable by said drill stem for'retaining'said blades on said body.

References Cited in the file of this patent UNITED STATES PATENTS McMurdy et a1 June 10, 1952 

